Everything becomes easier when you understand the fundamentals.
Modern scientists have managed to categorize all forces in the universe into four categories. Of course, four things implies that there is a single thing even more fundamental!
For now, this is the best we have until you come up with something better!
Your universe works based on a few rules that can be learned and predicted. In the beginning, energy condensed into strings resonating at specific frequencies. The frequency of the string determines a property about it such as mass, charge, color, spin, etc.
The Fundamental Forces are our way of understanding interactions between strings. When strings destructively interfere with each other, lowering the overall harmonic energy, an attractive force is felt by the interfering strings. When they constructively interfere, raising the energy, a repulsive force pushes the strings away from each other to undo the energy spike.
As of now, our understanding of the universe is incomplete and can therefore drastically change with a new discovery. However, our current description is suitable for describing nearly everything in the universe on a basic level. Gravity still has some kinks to work out but if neither Newton nor Einstein could figure it out completely, we’ll just have to work with what they did discover.