Should I have killed the snake?

Snakes of every kind do not bite without being provoked first. If someone is bit, it is either because they were harassing it or stepped upon it accidentally. Regardless, it is, at most, a fault of the victim, and natural selection running its course. If people watch where they step or put other appendages, be a responsible parent if they are and supervise their kids as they're supposed to do, and apply common sense when a snake is encountered, (in other words, leave it alone) then there is no risk of incident. In all, the snake is not any sort of severe public safety threat by any means. They want nothing more than to be left alone in peace.

Even then, there is no guarantee that you identified it correctly as a venomous snake, but venom or not, do not just kill an animal for mere existing. They're a good animal to have in the local environment as they play a vital role as secondary predators, and their population numbers are threatened as it is due to the aforementioned persecution for merely existing and being the center of irrational phobias for many people.

In all, the chance that an animal "might" be a threat in the mind of irrational phobics is never a valid reason to kill a wild animal.

Also, future advice, make sure you can properly identify the species of snake before handling it. Being unable to do so can at least cost you an entire limb, if not your life. And if there is a snake, or a bear, or a puma, or any other animal that could be potentially dangerous and is in an unwanted area, it is best to call a local parks and wildlife officer or animal removal specialist to have them properly relocate the animal, which is better - and safer - than outright killing it.

Most of the snakes that people claim are rattlesnakes are non-venomous. It's a good thing that you let it live.

When I was a grad student we could count on being called out every time there was heavy rain that forced snakes to higher ground. We were most happy when they reported coral snakes. Those were usually king snakes. The "cottonmouths" were water snakes of some sort. "Rattlesnakes" were usually DeKay's snakes. AKA brown snakes.

Did you take a pic of it? What makes you think it was a rattle snake.

Don't listen to lakelady if you want to keep your fingers

It's good that you left it alone. The snake won't hurt anyone unless they mess with it.

rattle snakes are benefical creatures they help maintain the rodent population better to let it go where you found it and consider yourself lucky you didnt get bit the baby rattlers are just as poisonous as the adults and as far as bitting someone they avoid human contact and only bite if they feel threatend in some way

never kill a snake, it is cruel and uncalled for.

A baby rattlesnake doesn't have enough venom to kill a bunny rabbit. It won't stay in the park. That kind of greenspace isn't it's desired habitat. It will move somewhere drier. Don't worry.

Sorry to say but it's probably to late. You might not find it. You should of put it I a box and took it to a pet store and asked them what to do. If you find it do that