Typically the left hand "ring finger" is reserved for a wedding band. People who wear rings for fun usually put them on other fngers

I've seen a couple of these switches before. Sometimes they have the line side already internally connected (or with a tab you can cut if you want them to be separate on the line side. I'd have to see a picture of the back side of it to tell you. But yeah you just need the one line side (with maybe a jumper if it is internally separated), and each switch leg connected to the other side of each switch.

If there is a ground stud on the switch (probably), ground it also.

If you looked at the pictures you could see why a layman is confused. The new switch isn't self contained with blue, red, white pigtails coming out of it. Why is the most unhelpful comment the most upvoted?

To add on, if you're trying to control 2 things separately, then only your double switch will work. Black from the group of 3 blacks should go to the line side of BOTH switches. The lone black and red will go to thr switched side, one on each switch. Leave neutrals and grounds all tied together

Hard to tell in the last picture how it was previously wired but what I'm seeing is top left with red and black are the switch legs for the light and fan respectively (are they the same appliance?) Top right/bottom right are just your 120v normal power just also using this JBox as an extra junction point. Is there an outlet below this switch?

Power comes in, power is also daisy chaining somewhere else. Also a double switch is there for co trolling 2 different things which is why there are 2 switch legs

K, there are also several cities in the US named Peru. OP is clearly talking about the country. They did not correct me when I asked

Perú* is a country, my good redditor

Ah ok. I'm a US citizen living in Arequipa. Beautiful city, beautiful country, amazing people

What city?