Best solution for code develop
The Git Server

It's best practice to setup a Git server for the team to access.  This way you have a central server that can be maintained, backed up, and focus on serving the source code.

While you could create your own, there are also several popular commercial options available that often have free private repositories (non-exhaustive list):


Bitbucket
GitHub
AWS CodeCommit


The Git server will just be a repository for your code.  It will allow for workflows like Pull Requests to better manage the changing code base.  However, the Git Server will not build your code or deploy it anywhere.

Jenkins

Jenkins will not actually store your source code.  Instead it is a tool used for Continuous-Integration (CI) and Continuous Deployment (CD), a big part of DevOps culture.  The basic idea is that the Jenkins server will take the source code put into your Git server, ensure it compiles, automated tests pass, and possibly even deploy to your test environment.  Tools like Jenkins work with multiple programming languages.  

Maven is a tool is specific to building Java projects.  Tools like Jenkins often have options to use Maven to build the project.

Setting up a CI/CD tool like Jenkins would be a great next step after you have a consistent place for everyone to store their code.

Best Solution

Gitlab, Bitbucket Pipelines, Azure DevOps are just three examples of tools that both house Git repositories and can do CI/CD. There are many options available for Git and CI/CD, and you can even combine them if you choose not to select an all-in-one solution.  Which tools are best is opinion based, and the best practice is to use a tool that helps manage your Git repositories and a tool for CI/CD.