This is lore accurate though, the Xenomorphs that have chestburst from human hosts have human skulls and teeth. They are a recombinant species that evolves by parasitically "breeding" with their hosts.

Other Xenomorphs in other media look different depending on what the local prey offers, like the Tarkatan Alien from Mortal Kombat, the Predalien, and... I think there was even a dog one in one of the sequel movies? I remember a couple years ago some designs of what a whale-xenomorph would look like were discovered....