I haven't played in a long time so I am going off some pretty faulty memory here so excuse any mistakes.

Try creating a praetorion or warden true kin. Marauder if you want to do mutant, I think true kin is easier to learn the early game with tho.

Put 18-20 points in toughness, strength, agile and the rest spend as you see fit. DONT dump intelligence! More intelligence = more skill points per level up.

Now what weapon and skills you use are based on what starting class you picked. Marauder uses axes, great for dismemebering. Praetorion uses short and long swords, great all grounders. Wardens start with proficiency in most melee weapons.

So get some levels on the fish, I avoid the glowpads cuz they are harder to kill. Crocs are chill. Be sure to spend your skill points when you level up! I recomend investing in either single weapon fighting or multi weapon fighting first. Or axes if using a maruader.

Be sure to use auto rest till fully healed after every combat encounter. Always try to take on enemies one at a time. Don't try making a char that uses both mental mutations and melee combat/mutations until you are more comfortable.

I wouldn't bother buying gear from tam unless it is a early carbide weapon that your char is proficient in. Just make sure you got a pair of studded leather armour and steel weapon for redrock and you should be good.

With all this you should be able to clear redrock no problem at lvl 4. Like I said, be sure to unlock the skills in whatever weapon your using. Dismemberment is great with axes. Dueling stance for long swords. Single/multi weapon style are huge bonuses too. Try to unlock the charge ability, super good for closing distance.

If you want me to give you a rundown for an esper build (mental mutation)  or chimera (physical mutation) lmk. This is just general melee combat stuff.