AD vs. AP vs. Bonus AD Ratios

After looking at some champions like Lee Sin, and Jarvan, I noticed that they have some very high base damage AND ratios on their skills. Jarvan has a 120% B. AD ratio and a 150% B. AD. Lee Sin has a 200% B. AD. Seeing these crazy high ratios got me thinking about how different is it from AP ratios. Is 120, 150, and 200% ratios normal for BONUS AD? Most mages have ratios that are 40 ~ 70% AP. Does that mean 120% B. AD = 70% AP?

Bonus AD and AP does not scale with level, and you start with 0 of both (excluding runes, masteries, and passives). You buy these stats as the game goes on, increasing your skills' damage as well. They are very similar, and then there's AD ratios. AD ratios seem much greater than both of these. You start with around 50-60 AD, and any AD you build will add on to this. Your AD also scales with level, making AD ratios much greater than the others. As I see it, it's:

AD > AP = B. AD

I just find it pretty crazy when I see a ratio over 100% on champions (Lee Sin, Jarvan, Vi, Wukong). Normally, the champions I play have about 40% - 60% AP ratios. Does this have to do with the prices of AD and AP items? If anyone can explain this, that would be nice.