pi, I would not say it was created by the Buddha. As Joseph Campbell put it nicely, when people asked the Buddha to teach them the truth, he said he would not teach them the truth but would show them how to discover it by themselves. That sums up Buddhism very well.
Also, it is not perfect understanding, but right understanding. Not a goal either, but one "eighth" of the eightfold path that leads to the end of suffering.
Last but not least, Buddhism is not slightly related to Zen. Zen is a school of Buddhism, within the Mahayana branch.
Is Buddhism a religion or a philosophy? I guess that varies from Buddhist to Buddhist. Personally, I do not like to think of it as either, but that is my choice. The Latin word religio literally means binding, and there is none of that in Buddhism. Philosophy, perhaps in its literal sense as "love for wisdom." Then again, Buddhism is not about wisdom (though wisdom, prajna, is certainly a part of it), but about freedom from suffering.
To me, Buddhism is a way of looking at reality which defies any definition. When asked what Buddhism is, I generally just shrug my shoulders and say, Buddhism is Buddhism. I know that does not help much, but it expresses my own understanding of Buddhism as being so unique that no words can describe it.
I am not the only one who can simply define it: Witness the use of koans in Zen Buddhism.