How to identify a project (eclipse) type (RCP or other) to look at the code?

Please bear with me, if my question sounds bad.

I am working with a project (java eclipse), I had the code base in my office laptop, it works fine, now I need to get inside the code/project so that I can modify when needed.

I can code in java (intermediate level), but I am a beginner at eclipse stuff, specially eclipse application/plugins.

I am spending lots of time reading/watching different tutorials on eclipse (like vogella, o7planning, help.eclipse, etc.) but got confused on all these different stuff, RCP, SWT/jFace, Java GUI, windowbuilder, etc.

I need to know How "this" (my project that I'm working) got started? Is it a eclipse RCP? seems like a RCP, but there is no OSGi,

Here is a list of what it has (other than .java, JRE library, Plug-in dependencies),

META-INF, build.properties, a product file, a launch, h2 connectivity, a plugin.xml

From user point of view, this program has several menus, views,

I was able to open some views in windowbuilder editor (not all views/menus)

some java classes named as handler (part of name).

Any suggestions (reading materials) how to start with this project to understand it completely will be really helpful.

Is there any way to reproduce the whole project (using all the codes/java files that I already have)?

One way to do reverse engineering is by going through plugin.xml.

vogella is a good tutorial you will find all major eclipse rcp related tutorials.

You mentioned menu go through your plugin.xml you will find org.eclipse.ui.menus extension and associated handlers.
https://www.vogella.com/tutorials/EclipseCommands/article.html

Do your plugin project contains.xtend files go through https://www.eclipse.org/xtend/documentation/101_gettingstarted.html

Do your plugin project contains xtext files go through DSL
https://www.eclipse.org/Xtext/documentation/102_domainmodelwalkthrough.html