The operative word here in Rom 8:19 is κτίσις (ktisis) which occurs about 19 times in the NT. It is most often translated as "creation", meaning "the sum total of everything created, creation, world" (BDAG #2b). For example:
- Mark 10:6, But from the beginning of creation, [God] made …
- Mark 10:19, … the beginning of the creation which …
- Mark 16:15, … the gospel to all creation.
- Rom 8:19, … For the anxious longing of the creation waits eagerly
- Rom 8:20, For the creation was subjected to futility, …
- Rom 8:21. that the creation itself will be liberated from its bondage to decay …
- Rom 8:22, We know that the whole creation has been groaning together in the pains of childbirth until the present time.
- Col 1:15, The Son is the image of the invisible God, the firstborn over all creation
- Heb 9:11, the greater and more perfect tabernacle that is not made with human hands, that is to say, is not a part of this creation.
- 2 Peter 3:4, For ever since the fathers fell asleep, all things are continuing as they were from the beginning of creation.
The same word can also mean an act of creation (BDAG#1), eg, Rom 1:20.
It can also mean the result of a creative act (BDAG #2a), eg, Heb 4:13, Col 1:23, etc.
The curse of sin affected more than just humanity: it affected all animals, and the rest of "all creation". Thus, "all creation is groaning" (death began after the first sin in Eden) while it awaits the final redemption/restoration of all things when death shall be eliminated (1 Cor 15:51-54).
This passage cannot be used as justification for Universalism (= all people will be save) because Jesus explicitly tells us in John 5:28, 29 (NIV), "Do not be amazed at this, for a time is coming when all who are in their graves will hear his voice and come out—those who have done what is good will rise to live, and those who have done what is evil will rise to be condemned."