I do have pale skin and brown hair so I get that some shadow will be there, but i feel like after using a mach 3 razor and shaving cream... my entire hairline is still visible. I at least want enough hair to be gone so that my hair isn't visible in pictures...
Or if that's not possible, is there a cream or something that i can buy to hide it?
As long as your hair is dark and your skin is pale, you will have a shadow, even with a close shave. If you just recently shaved, it will get better as your freshly shaved skin gains some color - some guys speed up the process with a self tanner lotion. However, I do not advise spending time out in the sun without a good sunscreen - the fresh shaved skin will burn quickly.
My hair has essentially all turned white/gray, so my shadow does not show. So you could hope that you turn gray soon.
get a bit of a tan, thats about all you can do
though it shouldn't be THAT visible if we're talking right after a shave. Are you shaving completely smooth, against the grain? (i know some don't do this, but it's perfectly safe to do, as long as you take care of your scalp health properly afterwards)
Laser is the only way to do anything about it.