why i am asked to present a model property release for my ownself photo or my own drawing?

There are a few issues that should be addressed with your submissions. First, to answer your specific question...the moderation team has no idea what you look like, so if you uploaded an image of yourself, you need to submit a model release with you listed as both the model and photographer. 

That's not the case with the two examples you shared. This are images of sketches. The concept noted above still applies. The moderation team has no way to know if you are the original artist that drew the sketches or if you bought an art book or went to a museum or coffee shop and snapped pictures of the drawings that were created by a different artist. As a result, you need to submit a valid property release that complies with our requirements confirming you own the copyright to the work. 

You applied a model release to the sketches which has multiple issues. One, as mentioned, it's a property release that is needed. Two, the model release you are using is not compliant with our requirements. Please review the release requirement sections of the legal guidelines HERE before moving forward. 

With all that said, even with a valid property release, your images will not be approved. You've submitted the files with a large signature on them. That's a guaranteed disqualifier so before resubmitting, you should remove that signature.

Good luck,

Mat 

Do they actually say "property release"? I'm going to assume so: a model release is where a human is represented. You just need to do what they say: fill in a property release as both "artist" (photographer) and "owner" (person who drew it). This is described in the documentation for filling in a release.