Archaeological findings and specimens suggest strongly that there once was a race of super humans, so large in general features that we could refer to them as giants. In Genesis 1 verses 1&2 we read two verses that have been interpreted to suggest several unknown years apart. For reasons unknown to us God deemed it wise to reveal only details of a creation only several thousands of years ago ... noting that the earth also created by God was already in existence in Genesis verse 2 but was in a formless, dark and empty uninhabited stage. The Bible does not explain the date of creation of the earth or give clues to its age. Job is once silenced in His pride by questions posed by God that relate to galactic mysteries he could never hope to answer. In the video (go to link) - Michael Tellinger presents what could be one of the best pieces of evidence that there were giants on Earth a long, long time ago. Geologists have marvelled at this giant foot print of over 4 feet long in rough granite.
Gen 1 In the beginning God created the heaven and the earth.  And the earth was without form, and void; and darkness was upon the face of the deep. And the Spirit of God moved upon the face of the waters.
Isaiah 48 You have heard [these things foretold], now you see this fulfillment. And will you not bear witness to it? I show you specified new things from this time forth, even hidden things [kept in reserve] which you have not known. (amp)
Proverbs 25 It is the glory of God to conceal a thing, but the glory of kings is to search out a thing.
Back to the issue of giants, there is an unusual verse that speaks of an extraordinary species of creation for which we have scanty information.
Genesis 6 There were giants in the earth in those days; and also after that, when the sons of God came in unto the daughters of men, and they bare children to them, the same became mighty men which were of old, men of renown.
Who were these sons of God ... a superhuman race of some sort of whom we are also not told of their creation? Will they ever be seen again?
Although, there are many views on the identity of the sons of God, I tend to lean on the fallen angel interpretation. According to this view, the ‘sons of God’ are fallen angels in the form of masculine human-like creatures. These angels married women of the human race (either Cainites or Sethites) and the resulting offspring were the Nephilim - with physical superiority and able to establish themselves as men of renown. This race was eventually wiped out by the flood, along with mankind in general except the eight in the ark. These fallen angels are part of the hierarchy of Satanic rebels banned from heavenly realms..
Job 1 Now there was a day when the sons of God came to present themselves before the LORD, and Satan came also among them.
Job 38 Where wast thou when I laid the foundations of the earth? declare, if thou hast understanding.  Who hath laid the measures thereof, if thou knowest? or who hath stretched the line upon it?  Whereupon are the foundations thereof fastened? or who laid the corner stone thereof;  When the morning stars sang together, and all the sons of God shouted for joy?
As the Bible does not date the age of the earth, nor do we know much about the morning stars or the sons of God ... the state of the earth between verses 1 and 2 of the first chapter of Genesis remains unrevealed in scriptures. We do know the sons of God had enough human features to procreate to produce a giant race also suggesting they must have been giants themselves. Some scholars have a problem of referring to “sons of God” as angels mainly because according to Matthew 22:29-30 angels neither marry or are given in marriage and are sexless ... others disagree suggesting that angels could be convincingly like men - as the men of Sodom were attracted to seek to rape the ‘male’ angels who came to destroy the city. (Genesis 19:1-5).
The Bible also speaks of the sin of angels who left their own habitation not satisfied with their dwellings in Jude verse 6 ... angels now reserved under chains. Where did they go and to do what? When were they chained? Will they be released for a time?
Jude And the angels which kept not their first estate, but left their own habitation, he hath reserved in everlasting chains under darkness unto the judgment of the great day.
Even after the Noah’s flood, it does seem this race may again have emerged as seen many years later in the times of Moses.
Numbers 13 And there we saw the giants, the sons of Anak, which come of the giants: and we were in our own sight as grasshoppers, and so we were in their sight.
Are we likely to see this race emerge again? Do we have extraordinarily gifted men of physical and mental renown today who are offsprings of fallen angels walking the earth today? ... children of sure perdition not wired for any kind of repentance ...genetically unrepentant to cause havoc in all spheres of life and annoy God ?
I cannot say...but the Bible does describe a time when evil will increase extraordinarily and reminds us that these days will be like the days of Noah ... suggesting that the things that happened in the days of Noah will be observed again in the last days.
Matthew 24  As it was in the days of Noah, so it will be at the coming of the Son of Man.
If giants and men of satanic genius and renown ever emerge again, normal intelligence and natural engagement will not suffice for their defeat. Be watchful ... pray and lean not to your own understanding. Do not permit any to distract you from the confidence you have as you remain in Christ. David had a rare encounter with these monsters but like David defeated Goliath, in Christ we are conquerors and overcomers ... and will have a sure victory through His Blood. Plead the sure victory that is only in the precious blood of Christ and keep praising Him.
Remember the Hymn “Thro' the precious blood of Christ we've victory ... If the Lord be for us we can never fail,...Nothing 'gainst His mighty power can e'er prevail...”
Remain always victorious and blessed.