Minecraft Bedrock Edition – Why All Downloaded Maps Have Seed 0?

Seeds are not “created”, they are found by trying them. The seed is called that because it is the seed value for a pseudorandom number generator which is then used to determine all of the attributes of the world; it is computationally infeasible to design a seed to produce a desired result.

Type something for the seed, see if you like the world, and if not, try again with a different seed. Or look for seeds other people have tried; there are many web sites which claim to provide such information.

Jim's method is about as good as it gets unless you don't require the world to be random. What I mean by 'not being random' is by using a seed where someone has identified a jungle at the game spawn point. Here are a few such seeds:

Large Jungle Biome - Seed:nopen

Jungle Island - Seed:agpiox

Enjoy