All is in God as God is omnipresent.
“All” contains many beings, not just humans in a physical body.
Angels are in God.
Jesus is in God.
We too are in God. (In many ways, we are asleep in God’s womb) and God is in us.
Omnipresent doesn’t mean God is “in” all of us, or that everything is “in” him. God is not an omnipresent pudding.
“We too all previously lived among them in our fleshly desires, carrying out the inclinations of our flesh and thoughts, and we were by nature children under wrath as the others were also....
...At that time you were without Christ, excluded from the citizenship of Israel, and foreigners to the covenants of promise, without hope and without God in the world. But now in Christ Jesus, you who were far away have been brought near by the blood of Christ....
...So then you are no longer foreigners and strangers, but fellow citizens with the saints, and members of God’s household, built on the foundation of the apostles and prophets, with Christ Jesus himself as the cornerstone. In him the whole building, being put together, grows into a holy temple in the Lord. In him you are also being built together for God’s dwelling in the Spirit.” - Ephesians 2
God has revealed Himself to us as male, though, so He doesn’t have a womb. And while from God’s Word we can say that in some senses everyone and everything is in God and perhaps in some way He is in us, since He has access to our whole person, including our thoughts and what’s going on in our hearts, we are certainly not at one — perfect oneness — with Him and He with us. We know God created everything and everyone through His Word, which is His Son Jesus, and that He breathed into Adam for Him to become a living soul (Genesis 2:7). We know that in the Lord we live and move and have our being (Acts 17:28), and that He gives light to every one who comes into this world (John 1:9). We know, as I mentioned, that He knows everything about us, including our thoughts, what’s in our hearts, and our spiritual condition. But clearly God’s Word teaches that rather than having perfect oneness with Him, we’re spiritually separated from Him and can only be reconciled to Him through believing on His Son, Jesus Christ, which means acknowledging ourselves to be sinners deserving of Hell and that only by God’s grace towards us, in Him giving His Son to atone for our sins, are we saved.