More build-a-spell analysis. This is the first time in the LBBs that we see magic-user spells that conjure or summon a creature (the Monster Summoning series of spells hadn't been added yet.) It's also the first time we see magic that affects souls/spirits (Mind Jar and, perhaps, Animate Dead.)
Teleport is Dimension Door with increased distance, added as a duration feature with the possibility of misteleport as a restriction on the unlimited distances allowed.
Hold Monster is supposed to be "Same as Hold Person but applicable to Monsters." But unlike the Charm Person/Charm Monster pair, no other differences are listed. The range for my modified Hold Person is shorter than the original, though, so we'll just add variable range. 2 Features + 3 Variables = 5th level spell.
Conjure Elemental is a conjuration (commands a creature to come and brings it to the caster: two Features.) It also requires concentration (duration feature) and the creature has HD equal to approximately triple the spell level (count as 2 features, to get the full 5th level.)
Telekinesis has a variable mass affected on top of the basic feature of "move object without touching." Since there's no note that it can't be used to lift an opponent, let's add that as an additional feature, plus two variables (range and duration.) 2 Features + 3 Variables = 5th level spell.
Transmute Rock to Mud is a basic transformation (feature) with variable area and range; duration is permanent until counteracted, but it can only be countered by the reversal of the spell. This counts as two features (duration feature + immune to Dispel Magic.) That might be a good template for permanent effects in general. 3 Features + 2 Variables = 5th level spell.
Wall of Stone, unlike Wall of Fire/Ice, lasts until dispelled and is tougher to break through (two features,) but doesn't cause damage as creatures break through. Wall of Iron is iffier than Wall of Stone, since you are replacing two duration features with one duration variable and trading size for increased durability, so we're one feature short. We can probably make up for it by adding the feature "merges with structure that can provide support".
Animate Dead turns inanimate objects (bones or corpses) into servants (1 Feature) and gives them limited autonomy (1 Feature.) Duration is "until dispelled" and "doesn't require concentration" (2 duration features.) Quantity is variable with level (1 Variable.)
Magic Jar places the caster's soul in an object (1 Feature,) gives the ability to sense creatures (1 Feature) near the object (1 Range Feature) and attempt to possess a creature (1 Feature.) The duration would be a feature as well, a variant of concentration required, with occasional power struggles with the victim's soul.
Contact Higher Plane is unnatural communication that gets answers to questions (2 Features) and has a "quantity variable" (maximum number of questions depends on HD/level.) Accuracy is dependent on both level and number of questions asked (1 Feature.) "Duration" as written is actually casting time for this spell, but we could add a feature that speeds up casting time for higher-level casters. 4 Features + 1 Variable = 5th level spell.
Pass-Wall is underpowered in terms of features and variables; it mostly seems to be 5th level because it's the "reverse" of Wall of Stone. It could be "pass through stone" + "passage is temporarily real, allowing others to follow" + "larger than man-sized opening", but even then, we only have 3 Features in the spell as written. We need to allow for variable length and duration to fit it into 5th level, giving us a more useful version of the spell.
Cloudkill is "create a cloud", "larger than man-sized area", "deadly poison", "movable at will".
Feeblemind explicitly trades a lowered saving throw for a restriction to a specific character class (Magic-Users.) We can consider that a "resistance feature", added to "permanent until dispelled", "reduces intelligence", "target loses magical ability", and a variable range.
Growth of Animals is Growth of Plants, but for animals, obviously. Instead of being permanent, it lasts for a set duration, which we can change to a variable, and instead of variable area, there's a fixed quantity. The extra level can be assumed to be because of the increased attack ability of the larger-than-normal beasts.