I never said that him outrunning Ishtar Familia was definitive proof he had Level 4 speed. You said that he never showed a huge advantage over her, and I gave that as an example that he indeed did. Also, it is explicity said that Phryne was the only one he couldn't surpass, and he managed to keep out of Aisha's grasp even when having to deal with an ever increasing number of prostitutes in his way. So if that isn't a huge advantage I don't know what it is.
Again, Bell had already fought Phryne. He wouldn't be fighting at his best unlike Aisha. Not to mention Aisha is a more skilled opponent and she could be higher in other stats than him. It's not that Bell didn't lack an advantage, that superiority in speed was making up for all the other disadvantages he had. And that he wasn't explicity said to boast a speed above his level doesn't mean he didn't have it. No one said he had Level 3 speed against Hyakinthos, even though he clearly did.
Level 1 Bell with S across all his stats besides Magic had to fight until he ended unconscious to defeat a Minotaur. A group of just three Level 2s with even just G in their stats can safely arrive to Rivira, which requires them to pass through three floors with dozens of Minotaurs and many others monsters as well. So yeah, even being low in a certain level is better than being high in the one below.
What's more, Oomori himself has mentioned a gap between levels. When hyping up Alfia and Zald he wrote this:
アルフィアやザルドのクラスになると レベル差を普通に覆してくるので、 ヘラの生き写しだと噂のLv.9女帝にも ワンチャンあります。
Rough translation:
When it comes to Alfia and Zald's class, the level difference is usually overturned, so the Lv.9 Empress, who is rumored to be a living copy of Hera, also has a chance.
Source: https://twitter.com/fujinoomori/status/1281196180009975809
What else was he talking about if not a power gap? Besides, "Alfia and Zald's class"? If it was really that easy to overturn it, as you claim it is, then why would he have to specify that "when it comes to Alfia and Zald's class"? Why would he specify that it is like that for her, who was repeteadly said to have unparalleled talent, and him, who had a skill described as "an unprecendted level of cheat", if not for it being something exclusive to increadibly OP characters such as them and not something common people can do, as you claim it is the case?
As for examples of the importance of level, here are some:
1. Gareth and Finn
While she joins them to fight Revis, Riveria is said to "be keeping up with their pace". That means they were moving at roughly the same speed. Gareth's Agility, however, was 295 points lower than Finn's. And that is just if you take into account their Level 6 stats. Who knows just how big that gap would be if taking into account their previous five levels. And yet there was Gareth, keeping up with Finn.
2. Lefiya and Luke
At Level 3 Lefiya's highest stat, besides Magic of course, was just at G270 last time we saw it. With her still limiting herself to being a mage, they wouldn't have grown a lot before her ascension to Level 4. Not to mention that her stats as a Level 1 and Level 2 would have been at best similar to those.
On the other hand, there is Luke. We don't know his stats, but he is said to be one of the best, and with the writer being Oomori that would entail having pretty good ones. Even if you leave that aside, the fact remains he is a melee combatant. At the very least one of his stats reached rank D, and the rest wouldn't be falling far off. Adding up their stats, Lefiya shouldn't be able to compare, yet she is both stronger and faster. Stronger even when up until Level 4 her Strength stat most likely never surpassed even rank I.
And she is also noted to be likely to win even if they were of the same level. A great gap, lacking the advantage of being a higher level, and she would still have a chance. Obviously that is because of her experience, but if the gap in physical prowess was big then her superior experience wouldn't matter. Like with Gareth and Finn, just being on the same level would put her abilities on the same league.
3. Asterius
Asterius has no technique, he is pure raw strength. But just having a Level 7's physical prowess was enough to not only overpower extremely skilled Level 6s, and be so superior he can keep up with three at the same time.
4. Bell vs Van
When he encounters Van, when thinking about his superiority Bell thinks something like "Lv5 and Lv 4, those numbers are absolute".
5. Bell and Hyakinthos
Hyakinthos wasn't just faster than Bell. He was so fast Bell couldn't even see his movements. Oomori justification? He is Level 3. And just that, because his Agility stat was just 519. Bell on the other hand had 1337 as a Level 1 and 741 as a Level 2 at that point. There Bell clearly had way more points than Hyakinthos, yet he was still massively inferior just because of being of a lower level.
6. Gareth and the Gulliver brothers
The Gullivers are Freya executives so they are obviously high Level 5s. And as Pallums tehir best stats would be Agility and Dexterity. Even Lyra was given a D in Agility, and she wasn't as much of a fighter as they are. Not to mention there is four of them. Yet, again, Gareth being just one level higher was enough to keep up with them all at the same time.
Not all examples show a superiority, but they do show the importance of level. Even with Gareth and Lefiya having inferior stats in past levels, all it takes for them to keep up with them would be being of the same level.
