Not by much. The average was lower, but people were still getting to more or less modern heights. A six foot tall man would have been considered tall, but not like a freak of nature or anything.

So roughly, there were three golden goddesses created the world and left behind the triforce, which has incredible power to shape the world (no gods can use it importantly). The goddess Hylia was in charge of protecting it. A super bad dude called Demise shows up and he wants that triforce to shape the world how he sees fit.

Demise is sealed away by Hylia but she is seriously wounded and also she knows the seal isn't going to hold. So she denounces her godhood and uses the triforce so that she can die and be reborn when Demise escapes the seal.

Fast forward a while and the seal fails. Hylia is reborn as Zelda. Hylia chooses a champion (Link) and he defeats Demise. But Demise is like "I'm not going away that easy. I will be reborn as many times as it takes!" And he has indeed been reborn several times as Ganon(dorf).

So Zelda, Link and Ganon are stuck in a cycle of rebirth all centered on the triforce. Or at least that's my understanding of the Creation period. I'm sure someone a little nerdier than me could pick it apart if they wanted to.