In this article, a comprehensive review of the integration of Unmanned Aerial Vehicles (UAVs) into shared airspace is presented. The primary objective is to underscore and gain a full understanding of the challenges, issues, and potential solutions related to regulatory frameworks, safety, and coordination. The methodology employed is a systematic review approach, which ensures the reliability and efficacy of the selected literature. The findings underscore the significance of various components, including multi-layered airspace models, path planning, secure communication networks, Conflict Detection and Resolution (CDR), and regulatory measures, in augmenting the safety of UAV integration. Additionally, the article explores the utilization of Reinforcement Learning (RL) and Human-in-the-loop Reinforcement Learning (HRL) algorithms as promising techniques for instructing UAVs to navigate complex environments and adapt to changing circumstances. The study emphasizes the importance of collaboration among all stakeholders, the support of technology development, and the need for continuous research.