Autism is investigated across multiple levels, including genetics, synaptic function, neural circuits, behavior, and social theory. Yet these perspectives often operate independently, leading to different and sometimes competing interpretations of what autism represents. This literature review examines how autism is defined and modeled across biological and social frameworks, with a focus on sensory development and heterogeneity. Molecular and animal research highlights altered synaptic plasticity, inhibitory signaling, and sensory processing, while genetic studies demonstrate that autism reflects multiple developmental pathways rather than a single biological mechanism. At the same time, social and theoretical scholarship argues that diagnostic categories are historically shaped and dynamically interpreted. Population-level surveillance data further show that patterns of autism identification change over time, suggesting that prevalence reflects evolving awareness and clinical practice in addition to biology. Taken together, these perspectives indicate that autism cannot be reduced to a singular essence. Instead, it emerges differently depending on the level of analysis and the interpretive frameworks applied. This review argues for a cross-level, humility-based approach that situates biological findings within broader social and developmental contexts. Rather than resolving autism into one definitive explanation, this review highlights the importance of examining how definitions are constructed across scientific and social domains.