Yeah, the distances in the simulation aren't really comparable to real life distances. They are only useful if you want to compare different creatures to each other.
As far as Unity and the physics system is concerned, the creatures are actually massive and the muscles are extremely powerful. Gravity is set to -50m/s² (in Unity meter units). I had to play around with these values a lot to get both natural looking behaviour and to get rid of as many unexpected physics bugs as possible.
So the fact that in the creature stats I write meters, doesn't mean actual meters. It's just because if I wrote "Average speed: 5 units/s" everybody would be asking what this arbitrary unit is, whereas its only purpose is to give you a comparison between creatures.