The 20mm eyepiece is a good model for the beginning. It provides 45x magnification, which should prove enough for a good amount of planetary and lunar detail.
The 4mm eyepiece belongs to garbage. Its eye relief is too short and provides too much power.
The 3x Barlow is useless. You simply can’t get quality images at such high powers with a small refractor. Adding to that, the mount doesn’t provide enough stability for that magnification range.
The 5×24 finder scope is another frustration. It is tiring to use. A red dot finder without any magnification would be simpler and easier to use. Especially for beginners.