You might have copied a different part, I’m not sure if this is just the quality of the image but both the right arm and the left leg has sharp edges. If so, that’s probably why it didn’t load the left part of the legs.
Here is an example:
Removing the humanoid would result to this:
You probably did something wrong while creating the model, try doing what the others suggested and it might solve your problem. Don’t worry you could do it.