The guys above have good advice.

The game is a procedural generation game, while it has rules, the generation can and will make bad seeds.
The usual rule is meadow, forest, swamp, mountain then plains, the generator may make a few mistakes, if you are playing solo... try another seed.
If you dont want to random a good seed, try the [search google Valheim map generator] for a solid seed, I did that as I had some seeds with a bad boss location.
Luckily you can generate nearly infenite number of seeds, so trying again is easy enough.