\input{} is putting the files at the end of the document instead of where I put them

Question

I have the following LaTeX file:

\documentclass[a4paper, 12pt]{report}
\usepackage{fancyhdr, caption, pgfplots, pdfpages, graphicx}
\pagestyle{fancy}
\fancyhead{}
\renewcommand{\headrulewidth}{0pt}
\setboolean{@twoside}{false}
\setlength\parindent{0pt}
\begin{document}
\includepdf[pages=-]{example-image.pdf}
\input{File 1}
\includepdf[pages=-]{example-image.pdf}
\input{File 1}
\includepdf[pages=-]{example-image.pdf}
\end{document}

File 1 is:

Some text
\begin{figure}
\begin{center}
\begin{tikzpicture}
\pgfplotsset{every x tick label/.append style={font=\tiny}, compat=1.3}
\begin{axis}[
    title={Title},
    xlabel={X Label},
    ylabel={Y Label},
    xmin=-100, xmax=100,
    ymin=0, ymax=145,
    ytick={0,10,...,140},
    xtick={-100,-75,...,100},
    ymajorgrids=true,
    xmajorgrids=true,
    grid style=dashed,
    legend pos=outer north east,
]
\addplot[
    color=blue,
    mark=*,
    ]
    coordinates {
    (-100,1)(-75,1)(-50,1)(-25,1)(0,30)(25,60)(50,105)(75,10)(100,13)
    };
\end{axis}
\end{tikzpicture}
\caption*{Caption}
\end{center}
\end{figure}

(In case it makes a difference, my actual file has more documents added to it than this, and the plots in File 1 and File 2 are different from each other and have many more addplots; I made this just as a MWE. It still reproduced the same problem when compiled.)

When I compile the document, all the \includepdfs are in the correct order, but the plots in both of the LaTeX files in the \input both go to the bottom of the document, even though I didn't place any of them there. The text in the \includepdfs stay in the correct place, but are separated from the plots. I need them to be in the positions I placed them in the file. They don't need to be on new pages (they're plots made with pgfplots), and (from my research) that's why I used \input instead of \include.

I also tried putting a line between each line of code but that didn't change anything.

What could be causing this problem?