Chula Vista

You're on the right track except you're overlooking one key component - weapons. The aliens planted the concept of using the bone (tool) as a weapon (via the monolith) to Moonwalker as a means to stave off the extinction of his tribe.

And when he tosses the bone in the air and we get that great jump cut to the ship thousands of years into the future what's not clear is that the ship is an orbiting nuclear "weapon". Look real closely as they show the various ships and you'll notice that each has the emblem of a different countries' flag. The earth is at a stalemate with all sides being capable of wiping the other out via their tools.

Why did the aliens bury the other monolith beneath the surface of the moon?

__________________

“The fact that we live at the bottom of a deep gravity well,
on the surface of a gas covered planet going around a nuclear fireball 90 million miles away
and think this to be normal is obviously some indication of how skewed our perspective tends to be.”