I will give you an answer that you aren't likely to get from any other individual here.
Let the universe be nothing but particles in the vaccum.
Now by definition, a point particle cannot be created and cannot be destroyed. Let the number of point particles at the beginning of time be denoted by N. The number of point particles at every moment in time from the beginning up to the present, was N. Thus, the derivative of N with respect to t is zero, that is
dN/dt = 0
Thus, point particles can only move relative to one another.
So then if the point particle model of the universe is the actual model, then the answer to your question is that the basic units of all larger material bodies did not ever come into existence, rather they were always there, from the first moment in time, right up to now.
Point particles have no parts, they cannot be created, nor can they be destroyed. The question then is, are point particles real entities, do they exist?
They would have no volume, and so it is difficult to imagine how two point particles could ever collide. But at the very least, the point particle model of the universe, models everything as some kind of huge point particle gas, and in certain regions of space, the gas is very dense, and forms large bodies of matter, including suns. It's just a model.