This is a young Northern Watersnake (Nerodia sipedon).

This is not a "coralsnake" in that it is not a venomous elapid snake like our US "Coralsnakes". The red next to yellow "rule" 1. only works in the US, except that it only works some of the time in some areas of the US. Some harmless snakes are red/yellow/black and have the red-against -yellow patterns. 2. only works some of the time in the US. Coralsnakes, like all other living species, are variable. I have seen coralsnakes that were almost solid black, had no black pigment at all, or had no yellow bands at all. Color is only reliable for identification if you don't mind being wrong some of the time, and in that case what's the point of the rule?

You don't say exactly where you are - for reptiles and amphibians, the locality tells which subspecies, but it is a baby Rat Snake. Rat Snake, WIkipedia Where you are is important to know what it will look like when it is grown. Totally harmless BTW, and can be picked up and played with.

Not sure where you are located but just generalizing, the head is the wrong shape to be one of the venomous North American snakes. The exception to the triangular shaped head would be the coral snake and it certainly isn’t one of those. Just leave it be and let it go about its business of eating vermin.