my Illustrator clip art file turns into a a black square when i convert it into a shape layer

That will not convert to a shape layer and retain the details of the photo. Just use the PSD in AE. There is no way to convert that clip art to a shape layer and retain any detail on the image. It will always convert to a solid.

If you just want the black outline then you will need to reduce the AI file to a simple object (path) and you should remove all of the other layers.

Probably a clipping mask could cause something like that.

you can release clipping mask in illustrator then reimport it back again  or once you convert it to shape layer, check the shapes created and see which one has a fill over the other layers and delete it

99% possibility that the artwork was improperly prepared in Illustrator. Each shape must be on a separate layer and effects, gradients, and clipping masks must be applied. No raster effects may be applied if you expect to convert the layer to a shape layer.

We can't know for sure what is wrong without seeing the layer structure and properties of the layers in AI. Unless you are going to use shape layer animators or actually animate the path of a vector file, there is no reason at all to convert it to a shape layer. If the problem lies with the conversion inside AE then we need to see all of the modified properties of the shape layer that was created. Just press the U key twice and show us the entire UI so we can see what is going on.

BTW, if the artwork came from Adobe Stock, you will probably have to Edit the original in AI and actually convert it to a path before AE can use it. It all depends on how the artwork was prepared in the first place.