why were ancient humans small, when almost everything (animals, dinosaur, plants, insects) that existed that time were massive?

Question

Edit: it’s been answered, it did slipped my mind that dinosaurs were long gone before humans.. I thought I was up to something, Thank you all!

In: Other

Answer 1

Dinosaurs (not all of which were massive), huge ferns and huge insects went extinct millions of years before humans appeared. At some point Earth’s atmosphere had more oxygen than it has now, allowing insects to grow large.

Also, there was plenty of small flora and fauna back there, just like today. And we have elephants and sequoias, so not everything is small nowadays.