The first earth age was inhabited by us, by our souls in a different form, there were no flesh bodies then. In that first earth age we all had spiritual bodies, in this earth age we have flesh bodies because we were created and formed from the dust of the earth. This is not reincarnation! Each soul can pass through each earth age only one time. For as it is written of our age:
"And as it is appointed unto men once to die, but after this the judgment" (Heb 9:27), no one is 'reincarnating' back in the flesh for second chances, there are no second chances.
When God destroyed that first earth age; the souls, the spiritual bodies, returned to the Father (God), just as we do when we die in this earth age. But spiritual bodies leave no organic remains. When we die today, only our organic remains (flesh and bone) remain to be buried. Our soul, our spiritual being or body so to speak, returns
instantly to the Father that gave it:
"Then shall the dust return to the earth as it was: and the spirit shall return unto God who gave it" (Eccl 12:7).
In this present second earth age we have two bodies, one within the other, and they can only be separated by death:
"It is sown a natural body; it is raised a spiritual body. There is a natural body, and there is a spiritual body" (1 Cor 15:44). But in the first earth age we only had the spiritual bodies. This isn't complicated to understand (although the corrupted end-time churches seem void of the knowledge) but you know that when someone dies today we bury their body, but their soul goes back to God that gave it.
" Then shall the dust return to the earth as it was: and the spirit shall return unto God who gave it" (Eccl 12:7). It is this soul that will be judged either to Heaven or
"Hell". But the deceased flesh that we bury simply rots back to the dirt and minerals that they are formed of, never to be used again.
Your spirit (your intellect) and your soul (your eternal self, the same 'you' in all three earth ages) will either live forever or will be consumed in the lake of fire
(Hell). Just as you will never find or see any physical remains of someone's soul, or spiritual body; neither will you find physical remains of those spiritual bodies that inhabited the earth in the first earth age, God took them all back, and there was no flesh to remain, for they were not flesh.
In the first earth age, man (us) was in a spiritual body, but the animals were in flesh bodies which is why we find animal remains dated back to millions of years old, but no human remains older that 14,000 years old (approx). In this our present second earth age, man (us) are also in flesh bodies as the animals but we are different from them in that we also have our spiritual bodies, or souls if you would, inside giving identity, intellect, and life to the flesh 'tabernacle'. These flesh bodies are carnal and weak to the pleasures and desires of the world. God regretted that He had made 'man' flesh in this second earth age because our spiritual selves succumbed to the carnal desires, lusts, and temptations of the flesh body:
Gen 6:3
3 And the LORD said, My spirit shall not always strive with man, for that he also is flesh: yet his days shall be an hundred and twenty years. (KJV)
Gen 6:5-6
5 And GOD saw that the wickedness of man was great in the earth, and that every imagination of the thoughts of his heart was only evil continually.
6 And it repented the LORD that he had made man on the earth, and it grieved him at his heart. (KJV)