While hummingbirds learn their songs from other hummingbirds, they don’t mimic human voices or other non-hummingbird sounds.
Hummingbird songs are in fact quite squeaky and simple. Here’s one example. Here’s another.
Interestingly, songbirds, parrots, and hummingbirds all share a similar brain structure that seems to be connected to vocal learning.
On another note (pun intended), contrary to that article it has now been found that songbirds and parrots are quite closely related, which could account for their similar learning abilities. However, hummingbirds are still thought to be only distantly related to those two groups.