True, all men have sinned and fall short of the glory of God. No one can be perfect or work their way into Heaven. That’s why we need a Savior.
Would you agree that there are Hebrews who preceded Christ’s first coming that are with God? Just read Hebrews 11.
The new covenant is conditional but the only condition is belief in the atoning sacrifice of Christ for the forgiveness of sins and His imputed righteousness for salvation.
“Come to Me all you who are weary and burdened, and I will give you rest. Take my yoke upon you and learn for Me, for I am gentle and humble in heart, and you will find rest for your souls. For My yoke is easy and My burden is light.” — Matthew 11:28-30
Well, we know Elijah and Enoch are with God as well as Moses. After that it is speculation.