Do physicists currently believe in a fundamental subatomic particle that is the building block of all matter?

The ancient Greeks created the concept of the "atom", a fundamental particle out of which all other matter was constructed. In the seventeenth, eighteenth and nineteenth centuries, European scientists adapted the Greek concept of the "atom", to represent the fundamental elements of the periodic table, out of which all chemical compounds were created. In the late nineteenth and early twentieth centuries, physicists speculated about splitting these chemical elements, and determining the fundamental "subatomic" particles. Subsequently, in the mid-twentieth century, the atom was indeed split. By the late twentieth century, innumerable subatomic particles were being analyzed and classified from huge particle accelerator experiments. I was wondering if, at this time, physicists still believe in some fundamental building block of all matter at the subatomic level, and what it might be. Or, do physicists see the subatomic universe as a kind of infinite regress, where an infinite number of types and varieties of particles exist, no single one of which can possibly explain all the rest.