First-tone 背 = the physical or figurative act of carrying weight on your back: a child, a backpack, a debt, or blame (背锅). The fourth-tone 背 sense (back of body / to recite) is a separate entry.
memory
Think of 背 as the action verb and 背 as the body part. Carrying something? First tone. Talking about the body part itself or reciting from it? Fourth tone.
Bottom ⺼ is the flesh radical (a variant of 肉), visually identical to the moon character but semantically a body marker. Groups 背 with the anatomy family: 胸, 腰, 肩, 肚.
Top 北 supplies the sound (běi shifts to bēi/bèi) and the original picture: two people standing back-to-back. Hence 背 literally means 'the body part that 北 points to' - your back. Houses face south, so the back faces north.
