This is wrong. At 2nd level, I can have a Str/Dex combo that has a +11 to AC and 2d6+9 damage (brutal 1) on a regular unmodified melee basic attack.
Two slayers, one Half-Orc and one Human, with the same starting array (18,14,11,10,10,8).
Half-Orc Slayer - 20 Str / 16 Dex
1 5/3 = 8
4 5/3 = 8
8...