I don't think anyone who is educated thinks heat is a fluid.
I don't think anyone who is educated thinks heat is kinetic energy.
Temperature is the average translational kinetic energy of the atoms in a material. When a material with a lower temperature (lower translational KE) is in contact with higher temperature material, the high KE atoms will transfer some their energy to the lower KE atoms. The transfer of this energy is called heat. The KE of the atoms is called temperature. The hot material will continue to transfer it's translational kinetic energy to the cooler material until the 2 bodies are the same temperature (the same translational KE energy level). The exchange of translational kinetic energy between the 2 bodies is often referred to as heat flow, but of course there is no actual flow of any material, just a transfer of energy.