If man is millions of years old as evolutionists claim
Evolutionists claim no such thing. The species homo sapien is generally considered to be about 300,000 years old.
For most of that time, they lived primarily as hunters and gatherers. It is generally believed that they began forming civilizations about 15,000 years ago, though scientists disagree on that number.
300,000 or a million. It's still not believable that man was smart enough to use tools but not smart enough to realize that plants grow from seeds and start planting what he liked.