what does it mean to say an object exists? In my thinking objects exists because subatomic particles/superstring vibrate or is in motion. what did pre-scientific thought think to the question, what does it mean for an object to exist?
Existence is a simple but elusive question, especially in philosophy.
The simplest answer is that an object exists "if one can see that it is so." This approach goes back to Aristotle's writings on epistemology (theory of knowledge).
However, what if I can see something that others cannot?
To resolve this problem, one can adjust the answer to "an object exists if there is consensus within a community of sentient beings." This removes any subjective variances of sensory perception.
But what of object like God, or the subatomic particles that you refer to? Where are they? Show me a quark, or God. You can't. So now existence depends upon what can't be directly observed yet nevertheless is the result of consensus among religious believers or physicists?
Thus begins the philosophical investigation of existence, knowledge, belief, and the distinction between these concepts.
A good introduction to philosophy will help get things sorted out, at least initially. Bertrand Russell's "Introduction to Philosophy" is a great place to start.