AI Files Opening as Images

I just downloaded the free trial of Adobe Illustrator and am so excited to start using it! I downloaded some AI files online from a few different sources. Every time I open them, they have the blue cross on it (assuming that means it's an image), and I'm not able to edit the elements of the image. I can't ungroup them or release any clipping masks, so I'm assuming its uploading as an image file (even though every file I've uploaded says it's an AI file...)

I also tried to 3D inflate these files, but I always get the error message: 3D objects only work on some objects and do not work on multiple instances (which provides further evidence to the above problem). 

Any suggestions on what I should do? Thanks in advance for the help!