I found out i made a mistake on my first post/question.
The JRE installer is working 100% correct, i made some errors myself i it seems i didn't unpack the JRE but another ZIP. So the JRE is not the problem. I apologies for this.
But since i started this thread i want to provide more info on the other error, so you might look into it.
When you try to install the WAR onto a fresh tomcat installation it fails with this error:
Caused by: org.springframework.jmx.export.UnableToRegisterMBeanException: Unable to register MBean [org.apache.tomcat.dbcp.dbcp2.BasicDataSource@6fc61d] with key 'dataSource'; nested exception is javax.management.InstanceAlreadyExistsException: Catalina:type=DataSource,host=localhost,context=/ganib,class=javax.sql.DataSource,name="jdbc/GanibDB"
I altered the context.xml from tomcat to have the correct jdbc connection, and during the activation of ganib you see that there is a short MySQL connection from Tomcat to MySQL. But then the error comes up and Tomcat disables Ganib.
I tried to disable the JDBC references in webapps/ganib/WEB-INF/web.xml, WEB-INF/classes/bussinessContext.xml but no luck.
My best guess is that Ganib needs to be on the root (like the JRE does) and not as a seperate webapp.