I've no idea if this is basic or what but I have this data that contains multiple lines (forming a polygon shape). I want to convert those lines (multiple - each with a start and end point) to a single line. I tried dissolve, multipart to single part etc. I cannot use topology since it influences precision. I have zero knowledge of programming.
If your lines are already in the same data layer, then you won't need anything from the toolbox -- just use the Editor, and follow the instructions in "Merging features in the same layer."
If you have different layers, first Merge them into one layer (Data Management | General | Merge), and then merge the features together using the Editor.
Not sure if this will work in your case, but suggesting to try the option "Convert Multipart Shapes to Single Parts" of "XTools Pro - Extension for ArcGIS"