One of the first decisions you will need to make in Biomutant revolves around creating your character. You will need to pick the breed you wish to play as, and this in turn will impact your stats. The beauty of character creation in Biomutant is that every decision impacts how your character looks, and how they plays, so if you want to really min/max a character you need to be aware of what to do right from the start.
The good news is that if you make some bad decisions then the stats increases are not so huge and significant that a character becomes unplayable, as you can still alter all stats while leveling up, and through gear. There are six Breeds in total to choose from, and each one is more suit to a specific role in the game.
Primals tend to be nimble and dexterous, and are best suited to builds that want to take advantage of Luck and Critical Chance. The have poor Power, Ki Energy, and Energy Regen, which means that are not the best at builds that want to take advantage of Ki abilities. Quick and speedy Deadeye builds are good for Primal breeds.
Dumdon are the best for melee focused builds, packing the high melee attack damage out of all breeds. Their low health means you want to lean into fast, quick hitting builds centered around dual wield or one-handed weapons.
When you are not sure how you want to play, Rex is the way to go due to the even distribution of stats for this build. You can then build however you like as the game goes on, and know you have a solid foundation in all directions.
Really good armor and health stats make the Hyla a reasonable tank, although no real such class exists within the game. You never really want to have to rely on just eating damage in a boss fight, but if you are worried about your ability to dodge and parry, then the Hyla might be for you.
Fip is essentially the caster build, and is where people who want to play with a lot of high-damage from abilities and general spell spam should focus.
If you have more fate in the gear you wear than your own body, then Murgel is the way to go. With the best loot and barter stats, you will be rolling around in high-level loot and crafting parts.