Can't manage to extract or convert SWF file because they seem to be corrupted

So I've extracted from a website a bunch of swf file which are photos.

What I was intending to do is converting them using swf tool.

However whatever I'm trying on thoose I'm ending up with :

./503141211.swf is not a valid SWF file or contains errors.

For exemple I've tried to render them with :

swfrender 2773003.swf -o test.png

Any idea why this is happening?

You can find one of the file there if you want : Link to file

Otherwise do you have a solution to extract an image from this link?

Your SWF files are already in JPEG format.

Solution: Try renaming them from .swf to .jpg.

Extended version:
If you ever suspect some file corruption, then first check the bytes with a hex-editor. Correct SWF beginning bytes are 43 57 53 (CWS) or sometimes begins with bytes 46 57 53 (FWS).

Your linked SWF file begins with FF D8 FF which is usually expected in JPEG files.
Also seeing JFIF signature confirms that this is a JPEG image file (not a Flash SWF file).

So after renaming from 3503270035.swf to 3503270035.jpg we get this result in image viewer: