What I mean is that God is all powerful. He has always existed and always will. Single-celled organisms have not always existed, and their "lives" can end. God did not gain his powers from anyone. He has always been omnipotent and eternal. You ask how we can be sure that He created us. How else would we spontaneously appear? It is true that we do not know what came before us. But the Bible says that the earth was "without form and void" so we can assume that God started with a shapeless earth, much like a blob of clay.
I was actually raised in a family that supported evolution. When I went to public school, I was taught the Big Bang and Darwinism and all that. But I started noticing some holes in the theory. For instance, mutations, almost always harmful, were supposed to turn microscopic cells into people? What about the lack of transitional forms in the fossil record? Carbon dating is determined by an equation missing two necessary variables. My grandma is a Christian and a Creationist, and she taught me some about Creationism. I read books, I did google searches, I watched debates on the subject. Finally, I decided that the evidence for Creationism overwhelmed that for evolution. When I asked a question about God, I would receive an actual answer that made sense. I made my decision to trust in Jesus Christ and God's Word in Genesis 1. No one should put their faith in something blindly. Do some research. Check the facts. Then you can see for yourself that the Bible is the truth.
Edit: single celled, not single called.