Inuyasha Question

Ok, I'll assume people know about Inuyasha so, I'll ask my question.

Kagome can travel from the present to the past via a well.
With all the talk on tv shows about doing anything in the past can alter the future, why is it that in the very first episode, nothing in the future (Kagome's present time) wasn't altered as soon as she landed in the past? I would think her school outfit would be a prime factor.

Eh... I still like the show, tho.