I can't even imagine the impact they would have had on the evolution of our culture and religions if they'd stuck around. The "winning" religions hinge on humans having dominion over all other animals in clear-cut ways.

Might belief systems like Buddhism or Jainism be more hegemonic if there had been a bridge species to tell us we're not so clearly special. And if they'd stuck around, would we still be having such a nail-biting time threading the needle on this extinction event that's predicated on our dominant cultures seeing nature as "other.