<p>This study aims to evaluate the flexural performance, crack resistance, and mechanical properties of composite beams. It specifically focuses on the performance characteristics of locally available inverted L-type shear connectors, headed shear connectors, and concrete made with brick aggregates and stone aggregates. This study examined how headed and inverted L-type shear connectors affect the steel–concrete composite beam’s flexural and mechanical performance. Thus, the experiment maintained the concrete mix design and reinforcement ratio while varying headed and inverted L-type connectors. The impact of shear connections improves the structural performance of composite beams compared to non-composite beams without them. The ultimate load capacity, corresponding deflection, and midspan deflection curve were examined in relation to the experimental data. The test specimens' failure behaviour was also investigated. The concrete slab’s flexural shear cracking and the steel flange's local buckling caused the composite beams to fail. The CBHS specimen improves in load-bearing (46.84%) and deflection reduction (61.30%), while CBIB demonstrates consistency, CBIS variability, and moment capacity increases are minor, demonstrating CBHS's efficiency and optimization possibilities. The test results show specimens with headed shear connectors function better than those with inverted L-type shear connectors.</p>