Does not the fact that a camel's kneeling is done by presenting its knees contradict what linguists have said, that a camel's knee is in its hand, and that kneeling only occurs on the knees?

This issue is one of the well-known matters of scholarly disagreement, and there is latitude in it. The prayer is valid whether the worshipper places his hands or his knees on the ground first. The disagreement stems from the hadith: "When one of you prostrates, he should not kneel down as a camel kneels." The prohibition in this hadith is about the manner of a camel's kneeling, not about the limb upon which it kneels. The intent behind opposing the camel's manner is to place the knees down before the hands.