If the lineage that led to humans had fewer reproductive cycles that fit within a given time frame, then the faster reproducing animals and the animals that generated more offspring had more time to evolve because evolution is primarily driven through reproduction cycles and how many offspring you have (when there’s selection pressure). There’s epigentics to tweak things but the major driver is still a full reproductive generation. It’s obviously more complicated than such a simple model (eg crocodiles and sharks have been largely unchanged for a long time) but it’s a good rough first order approximation that satisfies the original statement. It’s more interesting to take a stronger intent of the author than nitpicking them being technically wrong with the idea they expressed.