Rashi (on Pasuk 9), Ramban, Rashbam (both citing Bava Kama, 94b) and Targum Yonasan: It is referring to a Shomer Chinam, whom the Torah renders not liable for theft (and loss). ¹

Ramban and Seforno: Because, whereas the current Parshah is referring to a Shomer Chinam, who tends to look after money and vessels without payment, the following Parshah (Pasuk 9-12) is referring to a Shomer Sachar, who generally looks after animals for a fee.

Shevu'os, 42a: To preclude where the claimant is a Cheresh, Shoteh ve'Katan, in which case one is Patur from a Shevu'ah. ¹

Yerushalmi Gitin, 5:9: To teach us that a Katan cannot even acquire for himself

Refer to 22:6:2:1.

Bava Metzi'a, 57b: To teach us via a 'K'lal ("Yitein") u'Perat ("Kesef O Keilim") u'Kelal' ("Lishmor"), that a Shomer Chinam only swears ¹ on things that, like Kesef and Keilim, can be moved and that have an intrinsic value

Shevu'os, 38b: To compare Kesef to Keilim in that, just as the vessels are two, so too must the minimum claim comprise two silver Ma'os ¹

Mechilta: From the word "Lishmor", which implies whatever he is given for safe-keeping.

Bava Kama, 93a: 'To look after', and not to destroy or to tear (or break), or to distribute to the poor. ¹

Yerushalmi Shevu'os, 8:5: 'To look after', and not to give as a gift to whoever he wishes. ²

Mechilta: Refer to 22:6:151:1.

Rashbam: Because, since the former is safekeeping inanimate objects, ¹ the owner knows that the Shomer will place them in his house together with his own belongings, which he guards with care; whereas the latter, he places in the field, ² and he expects him to keep a watchful eye on them.

Rashi and Rashbam (both citing Bava Kama, 63b): "Vegunav mi'Beis ha'Ish" is referring to the Shomer's claim (To'en Ta'anas Ganav) not to what actually happened, ¹ the Pasuk ends where his claim is substantiated. Whereas Pesukim 7 & 8 are speaking where his claim turns out to be false

Yerushalmi Shevu'os, 8:1: It implies that if the Shomer places the article on his (unguarded) roof, from where it is stolen, he is considered a Poshe'a and is liable. ¹

Bava Kama, 69b: "mi'Beis ha'Ish", 've'Lo mi'Beis ha'Ganav'

Moshav Zekenim: The owner must say 'here, guard this for me.' If he said only 'keep your eyes on it', he is not a Shomer, and he is exempt for [passive] negligence. If he gave it to another Shomer, and we know that Ones occurred, he is exempt; the Halachah does not follow Rava, who says that the owner can say 'I do not want my item in another's hands.' ¹ If one deposited with a woman in front of her husband, he is liable, as if it was deposited with him.