This Work Is an Attempt to Recreate Quantum Mechanics Conceptual Foundations. First, We Claim That the Wave Function In Quantum Mechanics Is a Definition of Random Discontinuous Particle Motion, and That the Wave Function's Modulus Square Gives the Particle Probability Density at some Space Locations. First, We Demonstrate That the Linear, Non-Relativistic Evolution of an Isolated System's Wave Function Obeys the Free Schr ̈Odinger Equation Due to the Spacetime Translation Invariance and Relativistic Invariance Requirements. Thirdly, We Argue That the Discontinuous Random Motion of the Particles Will Lead to a Stochastic, Nonlinear Collapse of the Wave Function. a Discrete Model of the Energy-Conserved Collapse of the Wave Function Is Proposed and Demonstrated to Be Consistent With Current Experiments and Our Macroscopic Experience. We Also Offer a Crucial Review of the De Broglie-Bohm Theory, the Explanation of Several Worlds and Other Theories of Dynamic Collapse, and Briefly Discuss the Question of the Incompatibility Between Quantum Mechanics and Particular Relativity.