Nails like humans and apes have seem pretty weak compared to claws, and even other tree-dwelling species have hooked claws.
In: 591
Nails provide counter pressure so we can feel with the ~~fremitus~~ distal phalange of our fingers (front face). Without finger nails there would be little counter pressure and our sense of touch would be much less sensitive.
Edit: this ladies and gentleman, is why you get 3 different college degrees and end up owning a nail salon. To be the top answer on ELI5.
Edit2: thank you for the award!
Edit3: Gold! Thank you thank you!
Edit 4: word correction
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