WIll try to explain in simpler terms, i was very confused what crop factor was and all the other jargon being tossed about when i started out too.
I'm not all too sure yet, but your eye's natural view is roughly the equivalence of 41mm or so, in terms of Focal Length.
Anything less will "zoom out" from the subject,
anything more will "zoom in" on it.
Many consumer grade DSLRs contain sensors which are small, or what you refer to as "cropped sensor".
For decades before digital imaging came about, we all used film. And your common film is the 35mm film, the stuff that you always see in photolabs.
As i mentioned, consumer grade DSLRs still contain sensors which are small, and so they are not the size of a 35mm. However, professional grade DSLRs contain sensors which match this 35mm size. Very costly to produce, and one wafer of silicon sensor material can only produce roughly twenty 35mm sized sensors. That means only about 20 cameras made for each wafer like that, as compared to many times more "crop sensors" being produced.
These are your "full frame" bodies, containing sensors the same size as your 35mm film.
Hope u understand better now, it took me some time too. The jargon and vocab is the most difficult part to learn, IMO.
I hope i haven't shared anything misinformed either, because i'm not exactly very experienced either
On a final note -
All focal length of lenses are EQUAL. It's a universal thing and does not vary from brand to brand.
All the focal length of lenses are also in accordance to the "full frame"/35mm based sensor. To determine your TRUE focal length of your current lens on your camera, determine the "crop" of your camera model's sensor (which varies from brand to brand / camera to camera), and then multiply your focal length by this crop.
E.g. - Lens says 50mm,
My body's crop is x1.5
= 50mm x 1.5
= 75mm