A.T. Robertson Commentary Hebrews 2:5

"For not unto angels did he subject the world to come, whereof we speak." — Hebrews 2:5 (ASV)

For not unto angels (ου γαρ αγγελοις). The author now proceeds to show (2:5-18) that the very humanity of Jesus, the Son of Man, likewise proves his superiority to angels.

The world to come (την οικουμενην την μελλουσαν). The new order, the salvation just described. See a like use of μελλω (as participle) with σωτηρια (1:14), αιων (6:4f.), αγαθα (9:11; 10:1), πολις (13:14).

Whereof we speak (περ ης λαλουμεν). The author is discussing this new order introduced by Christ which makes obsolete the old dispensation of rites and symbols. God did not put this new order in charge of angels.