Changing things a bit. Based on last question comment, the black going to the switch in box 1 is switched hot and the black going to the /3 cable is hot. With dumb switches, that's one of a number of possible, equally functional, configurations. But that won't work here - hot and switched hot need to be swapped.
Terminology: /2 = black/white/bare cable. /3 = black/white/red/bare cable. The individual colored things are called wires. The groups are cables. All grounds together and ignored for general purposes - they are important but since they all go together everywhere, they don't affect how things are connected.
Based on the pictures and description, what I believe to be the likely scenario is:
Box 1:
Remove the black wire from the switch. This wire is the switched hot. Put a piece of red tape on it.
Remove the black wire that is part of the /3 cable from the bunch of black wires. Put a piece of red tape on it.
Use a wire nut to connect the two "red" wires together. That takes care of switched hot - it now goes to switch 2.
Use a short piece of 12 AWG (14 AWG is OK if this is a 15A circuit) black wire to connect from the now-empty common screw on switch 1 to the bunch of black wires. *That takes care of hot - it now goes to switch 1.
That now leaves us with:
- /3 = travelers (red and white) + switched hot (black)
- Black on switch goes bundle of hots (incoming power distributed to multiple switches/locations) - "common" screw
- Red and white on switch go to the /3 - the other 2 screws
- Black from /3 goes to light fixture /2 cable
- White from light fixture /2 cable goes to white neutral bundle
- Use a short piece of 12 AWG (14 AWG is OK if this is a 15A circuit) white wire to connect from the neutral bundle to the switch, if the switch (as many smart switches do) requires neutral
In the case of adding a new wire to the black hot bundle or the white neutral bundle, you may need a new wire nut.
Box 2:
- /3 = travelers (red and white) + switched hot (black)
- Black goes to common screw
- Red and white go to the other 2 screws
In box 1 you have hot, switched hot, neutral, travelers - everything you could need for any kind of switch.
In box 2 all you have is travelers and switched hot. You can't put a smart switch here unless it repurposes one of the travelers as an always hot and it doesn't require neutral.
If you want to improve things a little for future reference, mark the wires as follows:
Box 1:
- Red and white on switch - mark both with yellow tape
- Black from /3 goes to light fixture /2 cable - mark both with red tape
Box 2:
- Red and white go to the other 2 screws - mark both with yellow tape
That way, looking at tape, and when no tape looking at the natural wire color:
- Black = hot
- White = neutral
- Yellow = traveler
- Red = switched hot
