Isis, how pants are supposed to fit depends on their style. Jeans are generally supposed to be form-fitting and dress pants are generally supposed to have more ease and drape rather than squeeze Of course, there are countless varieties of those types of pants with different fit requirements.
Where the waistband is supposed to sit depends upon whether they're meant to be low rise, mid-rise or high rise pants.
Judging from the photo of the pants on the model, these are meant to be low-rise pants. They're supposed to sit an inch or two below your natural waistline, which is the narrowest part of your body above your hips and below your bust (I do not mean to be overly obvious here, but I've been surprised at how many people don't know where their natural waist is...they assume it's where their waistband usually is, but fashions change.)
I wouldn't think twice about the back of the pants sitting higher than the front. I generally have the opposite problem. The pants were most likely designed for someone with a larger posterior than yours, so there is a longer seam from the crotch to the back waistband than you need to accommodate extra tush. To me, this is not a real issue.
In fact, I think the first pair of pants look fabulous on you.
I don't like the fit of the second pants at all. I haven't seen those pants look good on anyone. I think there's something wrong with that design.
The last pair is just too big.
I hope this is helpful!!!