These are just some ideas I came up with to make the game more intuitive and visually informative. I don't think they're perfect by any means and they could of course be refined further. But I think they can serve as starting points to come up with even better ideas.
Also I think all of these effects should be able to be turned on/off in the game settings if players prefer a more stripped down look.
I think the new health bars look great and they're a definite improvement to the game. That said I think a good way to express a champion's health more immediately would be to alter the character model's size. As a champion gains more max health their size could increase proportionally. Players new and old would be able to see immediately who on their team and the enemy team has a lot of max health without ever looking at an item slot or the density of lines on the health bars.
The biggest caveat I see with a system like this would be how this would affect hitboxes. If a champion's size increases with max health then wouldn't their hitbox increase as well? I feel like it would have to at that point because skillshots would be too annoying to land otherwise. But if the hitboxes did increase as the champ's size increases that might be an interesting tradeoff to building lots of health and could justify making tank items stronger to compensate. I don't know, I think it could be interesting.
What if as you stack armor your champion becomes more metallic? Think along the lines of 'metal mario' but less extreme/opaque unless perhaps you have 6 armor items in which case you would look completely metal. I feel like the champions in League have strong enough silhouettes to be able to pull this off without sacrificing game clarity elsewhere.
As you stack MR your champion would develop a translucent purplish barrier around itself similar in shape to Creator Viktor's recall to be able to distinguish it from things like Banshee's Veil/Hexdrinker/Night's Veil. As you add MR it becomes a deeper purple but remains very translucent. I think it should only appear based on extra MR from items though and not be affected by the base MR of a champion.
For these I think it might be cool to recycle the visual effect red pot and blue pot give off but make their size vary proportionally to the amount of ap or ad. And the color of the aura would be red/blue/purple in proportion to the ratio of AD to AP a player has. So if they have equal parts AD and AP then the aura would be exactly purple. Then for red and blue pot the extra AP and AD they give would just simply add to the size of the aura.
Again I think these visual effects should be able to be turned on and off in the settings based on player preference. But I think little touches like these would go a long way to make the game both more accessible to newer players/spectators as well as more intuitive for newbies and veterans alike. Let me know what you think or if you have any related ideas you think would be even better or would add visual clarity to different aspects of the game not mentioned in this post. Thanks for reading!