This paper reviews the generation of large primordial fluctuations and their implications for the production of primordial black holes (PBHs) and scalar-induced secondary gravity waves (SIGWs), with the aim of understanding the impact of loop corrections on quantum correlations and the power spectrum. It provides a detailed review of the standard model of the universe, including causal structure, inflation, quantization of primordial perturbations, and field theoretic techniques like the "in-in" formalism. The paper discusses the severe constraints on PBH production in single-field inflation due to quantum loop corrections, and explores ways to circumvent these constraints in models like Galileon inflation, multiple sharp transition (MST)-induced inflation, and stochastic single field inflation using effective field theory (EFT). It also analyzes the Dynamical Renormalization Group (DRG) resummation approach, adiabatic and late-time renormalization schemes, and their use in producing solar and sub-solar mass PBHs. The paper summarizes how SIGWs are produced in MST setups and Galileon inflation, and thoroughly discusses the PBH overproduction issue. It also covers the implications of large quantum fluctuations on the generation of SIGWs, the role of scalar-induced gravity waves in addressing the PBH overproduction problem, and the use of effective field theory methods in studying PBH formation and SIGW production. The paper concludes with a discussion of the implications of these findings for cosmology and high energy physics.This paper reviews the generation of large primordial fluctuations and their implications for the production of primordial black holes (PBHs) and scalar-induced secondary gravity waves (SIGWs), with the aim of understanding the impact of loop corrections on quantum correlations and the power spectrum. It provides a detailed review of the standard model of the universe, including causal structure, inflation, quantization of primordial perturbations, and field theoretic techniques like the "in-in" formalism. The paper discusses the severe constraints on PBH production in single-field inflation due to quantum loop corrections, and explores ways to circumvent these constraints in models like Galileon inflation, multiple sharp transition (MST)-induced inflation, and stochastic single field inflation using effective field theory (EFT). It also analyzes the Dynamical Renormalization Group (DRG) resummation approach, adiabatic and late-time renormalization schemes, and their use in producing solar and sub-solar mass PBHs. The paper summarizes how SIGWs are produced in MST setups and Galileon inflation, and thoroughly discusses the PBH overproduction issue. It also covers the implications of large quantum fluctuations on the generation of SIGWs, the role of scalar-induced gravity waves in addressing the PBH overproduction problem, and the use of effective field theory methods in studying PBH formation and SIGW production. The paper concludes with a discussion of the implications of these findings for cosmology and high energy physics.