Which version of dashboard are you using (ArcGIS Online, Portal version xx.x)?
In any case, when I configure a map with a selection tool in a dashboard, I do not necessarily see a tool for the simple select. I just click on the map as if I were seeing a popup. This selects my feature. Can you try that to see if that is what is going on with your selection tool?
Can you provide more details on not seeing all map layers? What do you mean?