Which hero is the best at level 1-1-1?

Splitting the troops is certainly an option.
Ivor against Shakti... Let's calculate.
The Trolls will reach the Elves by round 4 – by then, around 80 of them will have been eliminated. Against 10 Centaurs and 12 Elves – and we can already estimate the Troll attack. Yes, Ivor will handle this – even without retreating.

I think we're making a mistake – the Miner will clearly crush everyone. First, 12 Elves won't kill 80 Trolls in 4 rounds with basic archery. Second, the remaining 40 (at a minimum, I think it will be more) will easily defeat 10 Centaurs and 12 Elves. The only option is for the Elves to retreat, but I don't think that will work either.