Aquinas's views have been very influential, especially in Catholic thought. Some things are in motion, anything moved is moved by another, and there can't be an infinite series of movers. This is God. Some things are caused, anything caused is caused by another, and there can't be an infinite series of causes. This is God.
Every contingent being at some time fails to exist.
So not everything is contingent. So there is a necessary being. This is God. Some things are greater than others. Whatever is great to any degree gets its greatness from that which is the greatest.