The balance of the game is that every time you enter a new biome, you are a noob all over again. Your previous gear should enable you to kill the trash mobs of that area, and anything higher should be avoided until you upgrade.

Do you remember entering the black forest and getting stomped in your leather gear? Conquering the black forest gave you a false sense of confidence. This jump will take place in every biome, just that the swamp is the first time it really sinks in.

Go slow, use caution and run if necessary. Using the hoe to make dry paths will make it easier to run if you need to. You can outrun everything in the swamp except for arrows, and there are lots of trees for that.

Don't go in there without poison resist mead and your trusty hoe. Snipe things with your bow before they become a problem.