Natural bioactive compounds derived from plants have been central to human medicine since antiquity. Civilizations across Asia, Africa, and the Middle East developed complex knowledge systems that preserved the therapeutic value of medicinal plants. Today, this traditional wisdom intersects with modern pharmacology, biotechnology, and clinical research, leading to a renewed focus on natural molecules as drug candidates. Scientific evidence increasingly validates the efficacy, safety, and diverse biological effects of herbal compounds, including antioxidant, anti-inflammatory, immunomodulatory, antimicrobial, anticancer, and metabolic regulatory activities. However, concerns remain regarding standardization, toxicity, regulatory gaps, and herb-drug interactions. This review explores the continuum from historical ethnopharmacology to contemporary drug discovery frameworks, highlighting major bioactive compound classes, mechanistic actions, clinical evidence, and future prospects for integrating natural molecules into evidence-based healthcare. The rediscovery of natural bioactive molecules represents not only scientific advancement but a reconnection with longstanding traditional knowledge systems that may reshape the future of global therapeutics.