If you die without a will, your estate will pass to others through your state’s intestacy laws. If you have no children, then property will be disbursed to family members. If there are no heirs according to your state’s intestacy laws, then the state may acquire the property. So, even if you do not have children, you still need a will if you do not want the state to make decisions for you about who gets what from your estate.
Keep in mind you do not have to create a will to benefit only family. A will allows you to pass your estate in a way that will serve what matters most to you: this could be preserving the financial wellbeing of your partner, parents, or siblings, but also setting money aside for the care of a pet, or assisting a charitable organization aligned with your values.