There are a few things going on here.
First is that the line chart you are using is a "category" chart. The "dates" are just text and they will be placed evenly spaced across the X axis regardless of the values. The scatter chart is the only true X-Y chart where the X data must be numeric (numbers or dates or whatever) and it will be treated as such.
Second, you need to get it all into one table, then make a scatter chart. Actually, if you are plotting just the one row of each table (well, two rows technically with X = the dates and Y = the first row) you could make it from multiple tables and then deselect "share X values". It won't work if you plot more than the one row. Note that all X and Y data needs to be in data cells for a scatter chart, none in headers. The line chart and other category charts expect the X "data" in the header. So you'll have to set header rows to 0.
The wonkiness you are seeing with the chart is because your data for the line chart is in multiple tables. The first table you chose has three dates in the header row and the chart gets its first three categories from that. When you select the next table to include its data, the chart ignores the first three dates in that table because it already has the first three category names. It picks up one more date/category from the last column of the table. With the next table it ignores the first 4 dates because it has 4 categories already then picks up a few more in the rightmost columns. In the last two tables it doesn't use any of the dates because it already has enough. Then it plots the data. Column B of all tables is plotted as the 1st category, Column C of all tables is the 2nd category, and so on.
