Rights are what we agree to bestow on ourselves and each other.
Categorically incorrect. Were this so, then a right would be a fluid thing. It is not. You are confusing a right and a privilege. These are mutually exclusive concepts, having absolutely nothing to do with each other.
The only truely inalienable right to a living being is the right to die.
Oh dear... methinks you need to sit alone in a quiet, dark room, preferably in a comfortable chair and think on this for as long as it takes to become apparent to you just how mind numbingly wrong this is. It may take hours. Or years. Keep at it because if you really believe what you wrote, you're in a lot of trouble.
Some people will argue that people should have certain rights but they are not guaranteed unless people create an enforcement mechanism of those rights.
No. There is no such thing as rights that one should or should not have. Rights are facts. We determine privileges. Rights follow from the acceptance of the premise that we are each born as free beings, which in turn follows from an acceptance of the notion of equality (or more precisely, equivalence) between us all. If these two conditions are accepted as true, the rest follows axiomatically and apodictically. That much I can promise you.
You may think you have the right to an apple growing on a tree in your yard but if a person or animal takes and eats that apple before you get to it, you do not have the rights to that apple.
What you are describing has nothing to do with rights per se, but rather the violation of them. If an apple is growing on a tree on YOUR PROPERTY, you hold the right to dispose of that apple as you see fit. If someone else takes it before you can get to it and they do so without your consent, that is theft, which is a crime. That one commits a crime against you, it does not follow that the rights they violated in so doing did not exist. For example, by your reasoning you hold no right to your own life. I may therefore murder you with impunity because crimes are necessarily defined (albeit indirectly in some cases) as violations of the rights of others. If you have no rights to violate, then I can commit no crime against you no matter what I do. If you redefine "right" to be synonymous with privilege, then you are opening a huge can of worms because then one's rights are necessarily arbitrary and may be redefined at whim. How happy would you be if your right to life were legislated away? Not very, I would bet.
We can agree to enact laws to protect your right to that apple- it does not mean you will not lose that apple but if somebody takes it away they can be punished. This is also true of personal liberty. You may think you have the right to move freely but that can be taken away and again we can enact laws to punish people taking away your liberty but they are not truely inalienable since it is impossible to stop somebody from taking them from you.
You do NOT understand rights or the concept of inalienability.