Supposed to be un-numbered chapters keeping the number of the previous one?

First of all, English isn’t my first language so I’m sorry for any unclear information/mistakes !

I am typing an internship report and I have a problem regarding chapter numbering. I have an un-numebered introduction (for which I used chapter*{Introduction}, followed by three numbered chapters that appear normally. However, I have a conclusion and a bibliography which, although I named them using chapter*{Conclusion} and chapter*{Bibliography}, appear with the number 3, exactly the same as the third chapter.

To specify, I have a main file and I use input to implement separate files for each part. Here’s the code from the main page (I manually add the list of figures and Bibliography to my table of contents directly on it, but I also add the un-numbered chapters using for example addcontentsline{toc}{chapter}{Introduction} in the separate files).

documentclass{report} 
usepackage[utf8]{inputenc} 
usepackage{color} 
usepackage[T1]{fontenc}
usepackage[a4paper,left=2cm,right=2cm,top=2cm,bottom=2cm]{geometry} 
usepackage[french]{babel} 
usepackage{libertine} 
usepackage[pdftex]{graphicx} 
usepackage[colorlinks]{hyperref} 
usepackage[style=numeric]{biblatex} 
usepackage{titlesec} 
usepackage{amsmath} 
usepackage{appendix}    
addbibresource{biblio.bib}
begin{document}

input{title}

tableofcontents

listoffigures

addcontentsline{toc}{chapter}{Table des figures}
input{remerciements}
newpage
input{introduction}
newpage
input{entreprise}
newpage
input{stage}
newpage
input{travaux}
newpage
input{conclusion}
addcontentsline{toc}{chapter}{Bibliographie}
printbibliography


end{document}

Where does this problem come from and how can I solve it?
Thank you in advance for helping 🙂