\documentclass{article}

\usepackage[subpreambles=true]{standalone}
\usepackage{import}

\graphicspath{{images/}{../images/}}
 
\title{The Ultimate in Modularity}
\author{D. Zack Garza}
\date{\today}
 
\begin{document}
 
    \maketitle
 
    \section{First section}
    \import{sections/}{lecture1}
 
    \section{Second section}
    \import{sections/}{lecture2}
 
\end{document}