Unicellular and multicellular Organisms are best explained through design

Single Cells Evolve Large Multicellular Forms in Just Two Years
https://www.quantamagazine.org/single-cells-evolve-large-multicellular-forms-in-just-two-years-20210922/

The phylogenetic analysis of tetraspanins projects the evolution of cell–cell interactions from unicellular to multicellular organisms
https://www.sciencedirect.com/science/article/pii/S0888754305002156?via%3Dihub

The support for the transition from unicellular organisms (single cell) to multicellular organisms requires the emergence of several new biochemical systems. These systems include:

- pathways that transform cells from generalized forms into specialized forms during growth and development;
- mechanisms for the migration of cells in relation to each other during growth and development;
- structures that support cell-cell adhesions;
- and cell-cell communication mechanisms.
- All these systems must be implemented and operate in an integrated manner to support multicellularity.

The transition from unicellular to multicellular organisms depends on the emergence of several new intricate biochemical systems required. Biochemical systems, such as cell transformation pathways, migration mechanisms, cell-cell adhesion structures, and cell-cell communication mechanisms, are components specifically designed to enable multicellular viability. The interdependence of these systems is an indication that they were designed to function in a harmonious and integrated manner, in order to fulfill a larger purpose. The coexistence and coordinated operation of these complex systems is evidence that the transition to multicellularity was guided by a conscious designer, who anticipated the needs and challenges associated with this process. The irreducible complexity of these systems is a characteristic that contributes to a design, since the removal of any two components would result in a loss of functionality. The complexity of these biochemical systems and their harmonious integration are evidence that multicellularity was designed to fulfill a specific purpose, demonstrating the presence of an intelligent mind behind the diversity and complexity of life.